Heart valves are typically replaced due to birth defects, stenosis (narrowing) of the valve (in which case the heart must exert a great deal of force to pump the blood through the valve) or insufficiency or incompetence of the valve, whereby the heart is unable to prevent backflow of the blood. The diseased or damaged heart valve is removed from the patient and replaced with some type of artificial or prosthetic valve.
The three main types of prosthetic heart valves are mechanical, biological and homograft. A detailed description and background of these three types of prosthetic heart valves may be found in U.S. Pat. No. 5,163,955, assigned to Autogenics, assignee of the present application and incorporated herein by reference. These valves, however, have proven to be costly and present an increased risk to the patient with respect to durability and acceptability.
Most recently, autologous tissue valves, i.e. valves constructed with the patient's own tissue, have been investigated. However, since this type of valve utilizes the patient's own tissue, the valve must usually be assembled during the same surgical procedure in which the patient's diseased or damaged valve is removed. Therefore, valve assembly must be completed in a rapid and efficient manner to avoid further risk to the patient.
To construct an autologous heart valve, one typically fits or mounts the patient's tissue onto a stent or some other type of valve frame. This can be accomplished by several methods. In one conventional method, the individual valve leaflets are cut from a roughly sized piece of tissue and individually sewn or attached onto the frame. In another method, a single piece of roughly sized tissue is attached to the valve frame and the excess tissue is trimmed away. Both of these methods, however, have proven to be time-consuming and unreliable.
The above referenced '955 patent discloses a novel and substantially improved cutting die for quickly and precisely cutting autologous tissue into the desired configuration. This die, however, does not provide the major improvements and advantages which have been incorporated into the cutting die of the present invention. These advantages will become apparent from the Detailed Description of the Invention, considered together with the drawings and claims.